J Med Dent Sci ２０１４；６１： １７－２２

Background: Vocal cord paralysis (VCP) is one of the postoperative complications after radical esophagectomy. VCP may also lead to serious morbidities such as respiratory distress and aspiration pneumonia. Therefore, an early diagnosis of VCP is meaningful in the postoperative management of patients undergoing esophagectomy. We evaluated a new practical method for diagnosing postoperative VCP.Methods: The laryngeal assessment of 30 patients was performed, and the presence of VCP was inferred while the following 15 patients by endoscopy before extubation after performing consecutive radical esophagectomy in 45 esophageal cancer patients. The vocal cord mobility, including adduction and abduction, were assessed by inserting the tip of a transnasal endoscope near the vocal cord in the awake patients with orotracheal intubation on the first postoperative day. The presence of VCP was re-evaluated after extubation.Results: Eleven of the 30 patients assessed after radical esophagectomy had unilateral VCP and one patient had bilateral VCP. The abduction findings were useful for assessing VCP and the sensitivity, specificity, positive and negative predictive values and accuracy were 97.9%, 100%, 100%, 92.9% and 98.3%, respectively. The results of the

following 15 patients were closely similar.Conclusions: The VCP during orotracheal intubation is assessable by transnasal endoscopy.

Key words: Vocal cord paralysis, Esophageal cancer, Esophagectomy, Endoscopy, Recurrent nerve

Introduction

    R a d i c a l e s o p h a g e c t o m y w i t h t h r e e - f i e l d lymphadenectomy is frequently performed in Japan. There is a risk of vocal cord paralysis (VCP) due to recurrent laryngeal nerve injury caused by lymphadenectomy around the recurrent laryngeal nerve on both sides. Re-intubation is required if there is VCP on both sides, because it can lead to fatal glottic stenosis and difficulty breathing1-4. The presence of postoperative VCP must therefore be examined, because such patients may require re-intubation and be at an increased risk of developing respiratory complications5.   An evaluation of vocal cord movement using percutaneous ultrasonography after thyroidectomy and direct observation with a laryngoscope after extubation have been reported6, 7. The prediction of VCP by monitoring the recurrent laryngeal nerve during surgery8-11, and predicting a post-extubation stridor under cuff deflation during intubation based on the amount of air leakage have also been reported12-14. However, an evaluation just before extubation has never been reported, and there have been no reports of the evaluation of the vocal cord movement directly in an intubated patient.    We rou t i ne ly assess the l a rynx , pharynx , esophagus and esophageal conduit in all patients

Corresponding Author: Tatsuyuki KawanoDepartment of Esophageal and General Surgery, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, JapanTel: +81-3-5803-5252　Fax: +81-3-3817-4126E-mail: kawano.srg1@tmd.ac.jpReceived September 30；Accepted November 8, 2013

Original Article

Vocal cord assessment with transnasal endoscopy in intubated patients after esophagectomy

Akihiro Hoshino1), Kenro Kawada1), Yasuaki Nakajima1), Kagami Nagai1), Taro Sugimoto2) and Tatsuyuki Kawano1)

1) Department of Esophageal and General Surgery, Tokyo Medical and Dental University, Tokyo, Japan2) Department of Otorhinolaryngology, Tokyo Medical and Dental University, Tokyo, Japan

18 J Med Dent SciA. Hoshino et al.

who underwent radical esophagectomy the morning of postoperative day 1 (POD 1) by transnasal esophagogastroduodenoscopy (tnEGD). In this study, the presence of VCP was specifically evaluated by direct observation just before extubation of the orotracheal intubation tube. We herein report the procedures used for tnEGD on POD 1 and the results of the tnEGD assessment regarding the vocal cord function during orotracheal intubation.

Patients and Methods

  A total of 45 consecutive esophageal cancer patients who underwent radical esophagectomy accompanied with lymphadenectomy around the bilateral recurrent laryngeal nerves from March 2010 to February 2011 at Tokyo Medical and Dental University were enrolled in this study. The patients’ characteristics are shown in Table 1. All cases were staged according to the classification of the Union for International Cancer Control (UICC), seventh edition. The initial observation of the vocal cords by endoscopy revealed that none of the patients had VCP before surgery. The laryngeal assessment of 30 patients was performed (Study 1), and the presence of VCP in the following 15 patients was inferred according to the findings of vocal cord movement (Study 2) . The Sapient ia electronic endoscope system (Fujinon corporation, Tokyo, Japan) and a small caliber endoscope (EG-530N2 or EG-530NW) were used. An orotracheal tube measuring 7.5 mm in inner diameter was used for males, and a 7 mm inner diameter tube was used for females. The mobility of the bilateral vocal cords was assessed by inserting the tip of the tnEGD near the vocal cords after removing the mucus in the larynx in patients who were awake before extubation on postoperative day 1. The presence of vocal cord adduction and abduction were assessed, and adduction was defined as positive when the vocal cord became convex toward the center when producing a sound, and abduction as positive when the contact of the orotracheal tube and vocal cord disappeared during deep inspiration (Figs. 1A, B). Bi lateral vocal cords were observed again by endoscopy after extubation, and the presence of VCP was diagnosed compared to the preoperative state.  The study protocol was approved by the Human Ethics Review Committee of Tokyo Medical and Dental University (No1370), and a signed consent form was obtained from each patient.

Table 1. The background of the patients

characteristics number of patients (%)

Age

Median (range) 67 (40-77)

Gender

Male 41 (91.1)

Female 4 (8.9)

Tumor location

Upper thoracic 5 (11.1)

Middle thoracic 27 (60.0)

Lower thoracic 13 (28.9)

Histology

Squamous cell carcinoma 41 (91.1)

Adenocarcinoma 2 (4.5)

Adenosquamous carcinoma 1 (2.2)

Neuroendocrine carcinoma 1 (2.2)

pathological T status

T1 14 (31.1)

T2 7 (15.6)

T3 23 (51.1)

T4 1 (2.2)

pathological N status

N0 7 (15.6)

N1 16 (35.6)

N2 10 (22.2)

N3 12 (26.6)

pathological M status

M0 44 (97.8)

M1 1 (2.2)

pathological Stage

StageI 12 (26.6)

StageII 14 (31.3)

StageIII 18 (40.0)

StageIV 1 (2.2)

Neoadjuvant chemotherapy

Yes 4 (8.9)

No 41 (91.1)

19vocal cord assessment during intubation

Results

  Eleven of the 30 patients assessed after radical esophagectomy had unilateral paralysis and one patient had bilateral paralysis. Therefore, 13 of 60 vocal cords (22%) were paralyzed. According to our findings, adduction was positive in 36 and negative in 24 vocal cords. Thirty- three vocal cords were normal and three were paralyzed in the vocal cords with adduction, while 14 vocal cords were normal and 10 were paralyzed in the 24 with negative f indings. The sensit ivity, specificity, positive and negative predictive values and accuracy of the adduction findings were 70.2% (95%

CI, 58.6%-81.8%), 76.9% (95% CI, 66.2%-87.6%), 91.7% (95% CI, 84.7%-98.7%), 41.7% (95% CI, 29.2%-54.2%) and 71.7%, respectively. Abduction was positive in 46 and negative in 14 vocal cords. All 46 vocal cords with positive findings had normal movement after extubation, while one vocal cord was normal and 13 were paralyzed in the 14 cords with negative findings. The sensitivity, specificity, positive and negative predictive values and accuracy of the abduction findings were 97.9% (95% CI, 94.3%-100.0%), 100%, 100%, 92.9% (95% CI, 86.1%-99.6%) and 98.3%, respectively (Tables 2, 3).   The presence of VCP was inferred in 15 patients (30

Table 2. Findings of the vocal cord movement by tnEGD before extubation in the Study 1

A. Adduction

adduction

normal VCP

+ 33 3 36

- 14 10 24

47 13 60

B. Abduction

abduction

normal VCP

+ 46 0 46

- 1 13 14

47 13 60

Figure 1. An evaluation with a tnEGD in a patient under orotracheal intubation (Figure 1).The vocal cord on the right side was normal and that on the left side was paralyzed during phonation (A) and deep inspiration (B). Part A shows positive adduction of the vocal cord, with it becoming convex to the median on the right side. Part B shows positive abduction breaking the contact between the vocal cord and endotracheal tube on the right side.

A B

20 J Med Dent SciA. Hoshino et al.

v o c a l c o r d s ) b a s e d o n t h e r e s u l t s o f t h e formerevaluation. It was difficult to infer the vocal cord mobility of both vocal cords in one patient because of insufficient arousal of the patient. In 14 patients, accurate diagnosis regarding vocal cord mobility before extubation was possible in 27 vocal cords, and the accuracy rate was 96.4%. Twenty-one of the 27 vocal cords were inferred to be normal based on the positive findings of adduction in 15 vocal cords and negative findings in six vocal cords, with a positive finding of abduction in all 21 vocal cords. The other six evaluable vocal cords were diagnosed as paralyzed based on negative findings of both adduction and abduction. Although the status of paralysis could not be inferred in one vocal cord with a finding of negative adduction but positive abduction, it was finally diagnosed that the paralysis of the vocal cord was incomplete, i.e. paresis (Table 4).  The follow-up endoscopic examination performed six months after surgery revealed continuing VCP in four of the 20 vocal cords, i.e. 71% improvement.

Discussion

  Esophageal cancer metastasizes to the lymph nodes surrounding the bilateral recurrent laryngeal nerve in 33.6-38.1% of cases15, 16. Vocal cord paralysis due to recurrent laryngeal nerve injury occurs in 15.6-45.3% of cases treated by a thorough dissection of the region during radical esophagectomy1-4. The risk of bilateral recurrent laryngeal nerve paralysis is about 2.1-7.8%1, 2, 4. Emergency tracheal re- intubat ion or emergency tracheostomy is required for a fixed paramedian or median vocal cords on both sides, which cause respiratory problems due to glottic stenosis after extubation, and a delay of treatment can be fatal. Therefore, evaluation of the vocal cord mobility after radical esophagectomy before extubation is preferred if possible, because it would allow affected patients to avoid the risk of extubation.  Many different diseases, including central nervous system disorders, neuromuscular diseases, focal vocal cord abnormalities and peripheral neuropathy cause

Table 4. The tnEGD findings before extubation in the Study 2

A. Adduction

adduction

normal VCP

+ 15 0 15

- 6 7 13

21 7 28** except 2 vocal cords in one patient because of the difficulty to assess

B. Abduction

abduction

normal VCP

+ 21 1 22

- 0 6 6

21 7 28** except 2 vocal cords in one patient because of the difficulty to assess

Table 3. The results of the tnEGD analysis of the vocal cords before extubation in the Study 1

Perfomance MeasureEndoscopic Findings

adduction abduction

Sensitivity, % (95% CI) 70.2 (58.6-81.8) 97.9 (94.3-100.0)

Specificity, % (95% CI) 76.9 (66.2-87.6) 100.0

Positive predictive value, % (95% CI) 91.7 (84.7-98.7) 100.0

Negative predictive value, % (95% CI) 41.7 (29.2-54.2) 92.9 (86.1-99.6)

Accuracy, % 71.7 98.3

21vocal cord assessment during intubation

VCP17. VCP is usually recognized after extubation. Unilateral VCP causing respiratory failure has been previously reported18, and bilateral paralysis requires re-intubation to prevent respiratory failure due to airway stenosis. Predicting the occurrence of stridor just before extubation has been reported, but the quality of its usefulness remains controversial12-14, and it is difficult to predict respiratory failure and airway stricture after extubation. VCP has been predicted by monitoring the recurrent laryngeal nerve and adding electrical stimulation. However, although the negative predictive value for this strategy was high, the positive predictive value had a large range, thus making its usefulness unsatisfactory8-11. There have been no reports of direct observation to evaluate the vocal cord mobility just before extubation.   The tnEGD was first reported by Shaker19 in 1994, and it has since been widely used for the examination and treatment of a variety of condit ions. The advantages of tnEGD are: the gag reflex and stress on the cardiovascular system are decreased compared to conventional EGD20, 21, an ultra-thin scope can be inserted into a small space, and it has features supp ly ing a i r and water , in compar ison to a laryngoscope. A tnEGD can be inserted close to the vocal cords to observe them carefully under intubation. Vocal cord assessment before extubation utilizing the full capabilities of tnEGD was established in the present study in order to infer the risk of respiratory failure due to bilateral VCP after extubation.  The laryngoscopic characteristics of the VCP are foreshorten ing of the vocal cords , arytenoid displacement, decreased vocal process contact, bowing and ventricular hyperfunction7. The vocal cord is relaxed, and the loss of abduction and adduction are found in VCP due to recurrent laryngeal nerve paralysis22. In this study, findings of the loss of adduction and abduction were used to evaluate the presence of VCP before and after extubation.  The sensitivity and specificity of the adduction findings were 70.2 and 76.2%, respectively, and the sensitivity and specificity of the abduction findings were 97.9 and 100%, respectively. The reason for the differences oberved in the accuracy rate of the adduction and abduction findings is thought mainly be due to orotracheal intubation per se. Because adduction is more frequently disturbed by an intubated tracheal tube. Therefore, vocal cord assessment by evaluating the abduction findings before extubation appears to be a good indicator for inferring the presence of VCP after extubation. Although normal

vocal cord movement was inferred in one case based on a positive finding of abduction, the vocal cord was judged to be paralyzed after extubation. The vocal cord in this case had a slight movement without fixation, and was thus considered to be a case of paresis. The vocal cord movement in this case fully recovered on postoperative day 8. The clinical significance of paresis inferred before extubation is low, because cases with paresis commonly have mild hoarseness, closing of the glottis with speech action, and show improvement within a short time. One patient was also difficult to evaluate because the patient could not follow the instructions for speech action and deep inspiration due to insufficient arousal.  A method must be developed to estimate the vocal cord mobility before extubation with sedation, because mobility is difficult to assess with insufficient arousal. Methods such as the assessment of the asymmetrical respiratory variability and the direct stimulation of the vocal cords may be used to assess vocal cord mobility in a sedated condition.  In conclusion, it is possible to estimate the vocal cord movement during intubation. The abduction findings have high sensitivity and specificity to infer vocal cord movement during intubation under conscious sedation.

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